Transcatheter microwave antenna

Abstract

A method, simulation, and apparatus are provided that are highly suitable for treatment of benign prostatic hyperplasia (BPH). A catheter is disclosed that includes a small diameter disk loaded monopole antenna surrounded by fusion material having a high heat of fusion and a melting point preferably at or near body temperature. Microwaves from the antenna heat prostatic tissue to promote necrosing of the prostatic tissue that relieves the pressure of the prostatic tissue against the urethra as the body reabsorbs the necrosed or dead tissue. The fusion material keeps the urethra cool by means of the heat of fusion of the fusion material. This prevents damage to the urethra while the prostatic tissue is necrosed. A computer simulation is provided that can be used to predict the resulting temperature profile produced in the prostatic tissue. By changing the various control features of the catheter and method of applying microwave energy a temperature profile can be predicted and produced that is similar to the temperature profile desired for the particular patient.

What is claimed is:  
     
       1. A transcatheter microwave antenna, comprising: 
       a microwave transmission line having first and second opposing ends, said first end being adapted for connection to a microwave power source, said microwave transmission line having a center conductor and an outer conductor;  
       a microwave antenna disposed on said second end of said microwave antenna;  
       a layer of fusion material disposed radially outward of said microwave antenna, said fusion material being alterable from a first physical state to a second physical state to provide heat of fusion cooling adjacent said catheter during operation of said microwave antenna.  
     
     
       2. The transcatheter microwave antenna of claim  1 , wherein said fusion material is operable for being in a solid physical state prior to operation of said microwave antenna and is operable for melting to a liquid state during operation of said microwave antenna so as to provide cooling radially outward from said catheter. 
     
     
       3. The transcatheter microwave antenna of claim  2 , wherein said fusion material in said solid state is substantially flexible. 
     
     
       4. The transcatheter microwave antenna of claim  1 , wherein said fusion material is substantially transparent to microwave radiation so as to absorb little energy directly from said microwave radiation. 
     
     
       5. The transcatheter microwave antenna of claim  1 , wherein said fusion material has a melting point in the range of from approximately eighty to one hundred degrees Fahrenheit. 
     
     
       6. The transcatheter microwave antenna of claim  1 , further comprising: 
       electrical insulating material between said center conductor and said outer conductor, said microwave antenna being disposed within said electrical insulating material.  
     
     
       7. The transcatheter microwave antenna of claim  1 , further comprising: 
       an outer sheath surrounding said fusion material.  
     
     
       8. The transcatheter microwave antenna of claim  1 , wherein said layer of fusion material is in surrounding relationship with said microwave antenna. 
     
     
       9. The transcatheter microwave antenna of claim  1 , wherein said fusion material is comprised of a crystalline material. 
     
     
       10. The transcatheter microwave antenna of claim  1 , wherein said fusion material is comprised of a powdered material. 
     
     
       11. The transcatheter microwave antenna of claim  1 , wherein said fusion material is comprised of dibasic sodium phosphate. 
     
     
       12. The transcatheter microwave antenna of claim  1 , wherein said fusion material is comprised of phosphonium chloride. 
     
     
       13. The transcatheter microwave antenna of claim  1 , further comprising: 
       a tubular conductor to act as an attenuator of microwaves, said tubular conductor being mounted at or near a surface of said catheter and being axially positioned on said catheter adjacent said microwave antenna.  
     
     
       14. The transcather microwave antenna of claim  1 , further comprising: 
       a layer of material for absorbing microwave heat energy applied to one side of said microwave antenna so as to make said microwave antenna directional.